Commonly, a backrest of a sofa is provided with a pillow for people to lean. Typically, tilting angles of the pillow can be adjusted by an adjuster, so as to suit for different supporting angles demanded by different users to obtain a comfortable feeling.
A conventional adjuster for pillows generally utilizes a rotating plate connecting with the pillow. Users can apply a force to the rotating plate via the pillow, so that an inner gear connecting with the rotating plate is driven to rotate, and in turn, a relative movement between the inner gear and the outer gear is generated as a result of engaging. And the position of the outer gear could not be moved as the outer gear is withstood by a spring, thus a trend that the outer gear engages with the inner gear is always maintained. As a result, when the inner gear is rotated along engaging teeth of the outer gear, the outer gear must carry on one engaging process with the inner gear after the inner gear is engaged with one of engaging teeth, so as to achieve the angle location of the rotating plate and, in turn to adjust the pillow to a suitable position gradually. However, in the conventional adjuster, the location of the rotating plate is depended on elasticity of the spring applied to the outer gear. Thus the inner gear and the outer gear are hard to engage with each other as the spring is easy to be exhausted due to its strength is limited, or the inner gear and the outer gear are hard to localize as a larger force from the user is applied to the pillow. Therefore the supporting capability of the adjuster after localization is weak and limited.